TWI683572B - Video bit rate transmission control method based on dynamic picture information - Google Patents

Abstract

A video bit rate transmission control method, suitable for controlling the video bit rate of a surveillance camera, is implemented by a control processing unit and includes the following steps: (A) After receiving an image from an image capturing unit, according to a Encoding parameters related to the bit rate of the encoded image, encoding the image into a currently encoded image; (B) According to the currently encoded image and a background image related to a target scene, determine whether an action event occurs and a temporary Whether the occupancy rate of the storage unit is greater than a threshold value to obtain a judgment result; and (C) update the coding parameter according to the judgment result, and store the current coded image to one of a storage unit and the temporary storage unit By.

Description

Video bit rate transmission control method based on dynamic picture information

The invention relates to a transmission control method, in particular to a video bit rate transmission control method based on dynamic picture information.

With the increasing popularity of wireless networks, the Video Surveillance System gradually replaces high-cost wired networks with wireless mesh networks (Wireless Mesh Network, WMN). A wireless mesh network is a mesh topology network formed by radio. Its characteristic is a mesh network self-tuning mechanism. When one of the nodes in the network is unavailable or busy, it will automatically adjust the hopping path. Let the network continue to operate normally.

However, the bandwidth of the wireless network has certain restrictions. When multiple nodes transmit data at the same time, the closer the link to the aggregation node, the more data will accumulate, resulting in link congestion. The video bit rate must be reduced. In order to reduce the use of bandwidth, the video bit rate is directly related to the video quality. The lower the video bit rate, the lower the video quality. Therefore, when the link is congested, the video quality decreases and there are events. When this happens, the purpose of monitoring cannot be achieved.

Therefore, the object of the present invention is to provide a video bit rate transmission control method that can improve link congestion.

Therefore, the video bit rate transmission control method of the present invention is suitable for controlling the video bit rate of a surveillance camera that is connected to a surveillance server via a communication network and includes a configuration configured to continuously shoot a target scene for continuous generation The image capturing unit of the image of the target scene, a storage unit, a temporary storage unit, a transmission unit connected to the monitoring server through the communication network, and a control processing unit, the storage unit stores a Background image and an encoding parameter related to the bit rate of the encoded image, the temporary storage unit is electrically connected to the transmission unit, and is used to store the image to be transmitted by the transmission unit to the monitoring server, and the control processing unit The storage unit and the temporary storage unit are electrically connected. The method is implemented by the control processing unit and includes a step (A), a step (B), and a step (C).

In this step (A), after the control processing unit receives an image from the image capturing unit, the control processing unit encodes the image into a currently encoded image according to the encoding parameter.

In this step (B), the control processing unit determines whether an action event occurs and whether the occupancy rate of the temporary storage unit is greater than a threshold value according to the current encoded image and the background image to obtain a determination result.

In this step (C), the control processing unit updates the encoding parameter according to the determination result, and stores the current encoded image to one of the storage unit and the temporary storage unit.

The effect of the present invention is to update the encoding parameters according to the determination result to perform bit rate allocation of the encoded image, and decide whether to store the current encoded image first in the storage unit or directly to the temporary storage unit As the image to be transmitted, the transmission resources can be optimized to improve link congestion.

1‧‧‧ surveillance camera

11‧‧‧Image shooting unit

12‧‧‧Storage unit

13‧‧‧Temporary storage unit

14‧‧‧Transmission unit

15‧‧‧Control processing unit

100‧‧‧Communication network

9‧‧‧Monitoring server

201~216‧‧‧Step

31‧‧‧Coding module

32‧‧‧Encryption module

33‧‧‧Control module

34‧‧‧Switch module

35‧‧‧ sampling module

Other features and functions of the present invention will be clearly presented in the embodiments with reference to the drawings, in which: FIG. 1 is a block diagram illustrating an example of a video bit rate transmission control for implementing the present invention based on dynamic picture information A surveillance camera of the method; FIG. 2 is a flowchart illustrating an embodiment of the video bit rate transmission control method based on the dynamic image information of the present invention; and FIG. 3 is a block diagram illustrating the surveillance camera.

Referring to FIG. 1, an example is illustrated of a surveillance camera 1 that can be used to implement the video bit rate transmission control method based on the dynamic image information of the present invention. The surveillance camera 1 A monitoring server 9 is connected via a communication network 100, and includes an image capturing unit 11, a storage unit 12, a temporary storage unit 13, a transmission unit 14, and a control processing unit 15. In this embodiment, the communication network 100 is, for example, the Internet, and the monitoring server 9 is, for example, a surveillance center (Video Surveillance Center, VSC), but not limited to this.

The image capturing unit 11 is configured to continuously capture a target scene so as to continuously generate images of the target scene.

The storage unit 12 stores a background image related to the target scene and an encoding parameter. In this embodiment, the storage unit 12 is, for example, a local storage device (Local Storage), and the encoding parameter is, for example, a quantization parameter (Quantization Parameter, QP), but it is not limited thereto.

The temporary storage unit 13 is electrically connected to the transmission unit 14 and is used to store the image to be transmitted that is transmitted by the transmission unit 14 to the monitoring server 9. In this embodiment, the temporary storage unit 13 is, for example, a buffer, but it is not limited thereto.

In this embodiment, the transmission unit 14 transmits the image to be transmitted stored in the temporary storage unit 13 by using a network stack technology. The transmission unit 14 stores an application layer communication protocol with network congestion control capability. When the network link is unstable, the communication protocol makes the data transmission rate of the transmission unit 14 slow, but not limited to this.

The control processing unit 15 is electrically connected to the storage unit 12 and the temporary storage unit 13.

Referring to FIG. 1 and FIG. 2, an example illustrates how the surveillance camera 1 implements an embodiment of the video bit rate transmission control method based on dynamic image information of the present invention. This embodiment will be described in detail below.

In step 201, after the control processing unit 15 receives an image from the image capturing unit 11, the image is encoded into a current encoded image according to the encoding parameters and a previous encoded image. In this embodiment, the encoding method of the current encoded image is a video compression method based on the division of picture blocks, which divides the image into blocks and encodes each block separately. Each block records information such as a prediction mode, the quantization parameter, a prediction residual value, a prediction angle, and a motion vector. It is worth noting that the control processing unit 15 encodes the image using an intraframe coding technique or an interframe coding technique, and the encoded image encoded by the intraframe encoding technique is I Picture (I-frame), which does not refer to other pictures when compressing, the coded image coded by the inter-frame coding is called P-frame (P-frame), which uses the most recent I picture or P picture as the direction The reference picture of forward prediction is combined with motion estimation and transcoding to compress it. Therefore, if the gap between the image and the previous encoded image is too large, it is encoded by the in-frame encoding technology, otherwise, if the image is different from the previous one If the difference between the encoded images is small, the inter-frame coding technology is used for coding. The intra-frame coding technology and the compression method of the inter-frame coding technology are conventional technologies, so there is no need to add more details. Narrate.

In step 202, the control processing unit 15 determines whether the currently encoded image is encoded using the in-frame encoding technique (ie, determines whether the currently encoded image is an I-picture). When it is determined that the current encoded image is encoded by the in-frame encoding technology, the process proceeds to step 203; when it is determined that the current encoded image is not encoded by the in-frame encoding technology, the process proceeds to step 204.

In step 203, the control processing unit 15 encrypts the currently encoded video. In this embodiment, the control processing unit 15 perturbs the ordering of each block of the currently encoded image with a cryptographic table to encrypt the currently encoded image. In detail, when I-picture decoding fails, subsequent P-pictures that use the I-picture as a reference picture decode the wrong picture information due to the reference to the wrong block, resulting in an error propagation phenomenon. To achieve the effect of encryption.

It should be particularly noted that, in other embodiments, in step 202, after determining that the current encoded image is encoded by the in-frame encoding technology, the control processing unit 15 also determines whether the current encoded image is in the I-picture The IDR frame (IDR frame), when it is determined that the current encoded image is an IDR frame in the I frame, the flow proceeds to step 203; otherwise, the flow proceeds to 204.

其中N為該等區塊的數量，mv _i 為第i個區塊的動作向量，T _v 為該第一閾值，該控制處理單元15將動作強度大於該第一閾值的動作向量加總後，獲得一動作向量總和，若該動作向量總和大於一第二閾值，則判定有一動作事件，反之則無動作事件，如下式：

為該動作向量總和，T _e 為該第二閾值。 In step 204 after step 202 or step 203, the control processing unit 15 determines whether a motion event (Motion event) occurs, when it is determined that a motion event occurs, the flow proceeds to step 205; when it is determined that no motion event occurs , The process proceeds to step 211. In this embodiment, the control processing unit 15 uses the motion vector of each block of the current encoded image as a determination condition, in order to reduce the impact of the analysis result of the block with less motion intensity, so the motion intensity is lower than a first The action vector of the threshold is set to (0,0), and only the action vector with greater action intensity is retained, as follows:

Where N is the number of such blocks, mv _i is the motion vector of the i-th block, T _{v is} the first threshold, and the control processing unit 15 adds up the motion vectors with motion intensity greater than the first threshold, Obtain an action vector sum, if the action vector sum is greater than a second threshold, it is determined that there is an action event, otherwise there is no action event, as follows:

For the sum of the action vectors, T _{e is} the second threshold.

In step 205, the control processing unit 15 stores the current encoded image to the storage unit 12, and the bit rate of the encoded image encoded by the encoding parameter before update is less than that encoded by the updated encoding parameter The bit rate of the encoded image. In this embodiment, the encoding parameter is inversely related to the bit rate of the encoded image, but not limited to this.

In step 206, the control processing unit 15 determines whether the occupancy rate of the temporary storage unit 13 is greater than a threshold, and when it is determined that the occupancy rate of the temporary storage unit 13 is greater than the threshold (that is, the buffer queue length (Buffer queue length) level) is too long), the process proceeds Step 207; When it is determined that the occupancy rate of the temporary storage unit 13 is not greater than the threshold, the process proceeds to step 210. In this embodiment, the threshold value is, for example, a floating ratio, which is estimated by the control processing unit 15 according to the file size of the current encoded image and the number of frames of the video required for 1 second of video, to estimate 1 second of video The file size of the clock, and adjust the threshold to 1 minus the file size of the video for 1 second divided by the capacity of the temporary storage unit 13 (ie 1-video file size for 1 second/the capacity of the temporary storage unit 13) If the capacity of the temporary storage unit 13 is sufficient, the control processing unit 15 can also estimate the file size of the video for 2 seconds, and adjust the threshold to 1 minus the file size of the video for 2 seconds divided by the temporary storage unit The capacity of 13 (that is, the file size of 1-video for 2 seconds/the capacity of the temporary storage unit 13), in other embodiments, the threshold may also be a predetermined value, but not limited to this.

In step 207, the control processing unit 15 stores the current encoded image to the storage unit 12.

In step 208, the control processing unit 15 determines whether the currently encoded image is encoded using the in-frame encoding technology (ie, determines whether the currently encoded image is an I-picture). When it is determined that the current encoded image is encoded with the in-frame encoding technology, the process proceeds to step 209; when it is determined that the current encoded image is not encoded with the in-frame encoding technology, the current encoding stored in the storage unit 12 When the image is a P-picture, the process ends to encode the next image.

In step 209, the control processing unit 15 stores the current encoded image stored in the storage unit 12 to the temporary storage unit 13 as an image to be transmitted.

In step 210 after step 206, the control processing unit 15 stores the current encoded image to the temporary storage unit 13 as an image to be transmitted.

In step 211 after step 204, the control processing unit 15 stores the current encoded image in the storage unit 12, and the bit rate of the encoded image encoded by the encoding parameter before update is greater than that after the updated encoding parameter The bit rate of the encoded image.

In step 212, the control processing unit 15 determines whether the occupancy rate of the temporary storage unit 13 is greater than the threshold value. When it is determined that the occupancy rate of the temporary storage unit 13 is not greater than the threshold value, the flow proceeds to step 213; When the occupancy rate of the temporary storage unit 13 is greater than the threshold, the process proceeds to step 216.

In step 213, the control processing unit 15 stores the current encoded image to the temporary storage unit 13 as an image to be transmitted.

In step 214, the control processing unit 15 determines whether the storage unit 12 stores the previous encoded image. When it is determined that the storage unit 12 stores the previous encoded image, the flow proceeds to step 215; when it is determined that the storage unit 12 does not store the previous encoded image, the flow ends to encode the next image.

In step 215, the control processing unit 15 stores all the encoded images stored in the storage unit 12 to the temporary storage unit 13 as images to be transmitted. It is worth noting that since all the I pictures are stored in the temporary storage unit 13 in step 209, all the encoded images stored in the storage unit 12 in this step are P pictures.

In step 216 after step 212, the control processing unit 15 stores the current encoded image to the temporary storage unit 13 as an image to be transmitted.

Referring to FIG. 3, it is worth mentioning that the control processing unit 15 executes the control decision program stored in the storage unit 12 to provide different functions, and the control processing unit 15 executes different program fragments in the control decision program to Provide different functions, the control processing unit 15 cooperates with the execution of different program fragments, so that the control processing unit 15 includes an encoding module 31, an encryption module 32, a control module 33, a switching module 34, and a sampling Module 35 to provide different functions.

The function provided by the control processing unit 15 when executing the program segment corresponding to the flow of step 201 is regarded as the function that the encoding module 31 can provide. The encoding module 31 according to the encoding parameter and the previous encoded image will The image is encoded into the currently encoded image.

The functions provided by the control processing unit 15 when executing the program fragments corresponding to the steps 202 and 203 are regarded as the functions provided by the encryption module 32, and the encryption module 32 only disturbs the blocks of the I picture Encryption.

The functions provided by the control processing unit 15 when executing the program fragments corresponding to the steps 204, 205, 206, 207, 210, 211, 212, 213, 216 are regarded as the functions provided by the control module 33, The control module 33 generates different decisions based on a judgment result of whether an action event occurs and whether the occupancy rate of the temporary storage unit 13 is greater than the threshold value. The following details the decisions corresponding to the four judgment results Policy.

Type 1: When the result of the determination is that an action event has occurred and the occupancy rate of the temporary storage unit 13 is greater than the threshold, the control module 33 adjusts the encoding parameters to increase the bit rate of the next encoded image And store the current code to the storage unit 12.

Type 2: When the result of the determination is that an action event occurs and the occupancy rate of the temporary storage unit 13 is not greater than the threshold, the control module 33 adjusts the encoding parameters to increase the bit of the next encoded image And store the current code in the temporary storage unit 13 as an image to be transmitted.

Type 3: When the result of the determination is that no action event has occurred and the occupancy rate of the temporary storage unit 13 is greater than the threshold, the control module 33 adjusts the encoding parameters to reduce the bit rate of the next encoded image And store the current code to the temporary storage unit 13 as an image to be transmitted.

Type 4: When the result of the determination is that no action event has occurred and the occupancy rate of the temporary storage unit 13 is not greater than the threshold, the control module 33 adjusts the encoding parameter to reduce the bit of the next encoded image And store the current code in the temporary storage unit 13 as an image to be transmitted.

The functions provided by the control processing unit 15 when executing the program fragments corresponding to the processes of steps 207, 210, 213, and 216 are regarded as the functions that the control module 33 and the switching module 34 can provide. Group 33 switches according to the result of this determination The switching module 34 changes the storage path of the current encoded image. When the determination result is the first type, the current code is stored in the storage unit 12, and when the determination result is the second, third, or fourth type, The current code is stored in the temporary storage unit 13.

The function provided by the control processing unit 15 when executing the program fragments corresponding to the processes of steps 208, 209, 214, and 215 is regarded as the function provided by the sub-sampling module 35, and when the determination result is the first type At this time, the sub-sampling module 35 only samples and transmits I pictures to reduce the amount of transmission resources currently required and to provide monitoring personnel to ensure a certain level of monitoring picture quality when the link is congested. When the judgment result is the fourth type The sub-sampling module 35 samples and transmits the encoded image (historical video) stored in the storage unit 12 (local storage device) to provide the monitoring personnel with the monitoring screen temporarily stored during the peak period of the link.

In summary, according to the video bit rate transmission control method of the present invention based on the dynamic information of the picture, the control processing unit 15 updates the encoding parameters according to the determination result to allocate the bit rate of the encoded image, and decides to convert the current The encoded image is first stored in the storage unit, or directly stored in the temporary storage unit as the image to be transmitted. In detail, when an action event occurs, the encoding compression bit rate is increased to ensure the picture quality, and at the same time When the temporary storage unit 13 is in a congested state, it will store the current encoded image in the storage unit 12, and only selectively store the I picture to the temporary storage unit 13 to reduce the use of network transmission resources; and when there is no action When an event occurs, the information of the image is mostly a fixed background picture, so the codec is downgraded while ensuring the lowest picture quality Compress the bit rate to reduce the resources consumed during transmission, and at the same time, when the temporary storage unit 13 is not in a congested state, the encoded image stored in the storage unit 12 is transmitted to provide monitoring personnel to keep the location during the peak period of the link The temporary monitoring screen allows the transmission resources to be optimized to improve the link congestion to achieve the monitoring purpose, so it can indeed achieve the purpose of cost invention.

However, the above are only examples of the present invention, and the scope of implementation of the present invention cannot be limited by this, any simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the content of the patent specification are still classified as Within the scope of the invention patent.

201~216‧‧‧Step

Claims (7)

A video bit rate transmission control method suitable for controlling the video bit rate of a surveillance camera connected to a surveillance server via a communication network and including a camera that is configured to continuously shoot a target scene to continuously generate the target scene Image image capturing unit, a storage unit, a temporary storage unit, a transmission unit connected to the monitoring server via the communication network, and a control processing unit, the storage unit stores a background image related to the target scene and An encoding parameter related to the bit rate of the encoded image, the temporary storage unit is electrically connected to the transmission unit, and is used to store the image to be transmitted transmitted by the transmission unit to the monitoring server, and the control processing unit is electrically connected to the The storage unit and the temporary storage unit, the method is implemented by the control processing unit and includes the following steps: (A) after receiving an image from the image capturing unit, the image is encoded into a current encoding according to the encoding parameters Image; (B) according to the current encoded image and the background image, determine whether an action event occurs and whether the occupancy rate of the temporary storage unit is greater than a threshold to obtain a determination result; and (C) according to the determination result, Update the encoding parameters, and store the current encoded image to one of the storage unit and the temporary storage unit, wherein, when the determination result is that an action event is determined and the occupancy rate of the temporary storage unit is greater than the threshold Value, the current encoded image is stored in the storage unit, and the bit rate of the encoded image encoded by the encoding parameter before update is less than the bit rate of the encoded image encoded by the updated encoding parameter. The video bit rate transmission control method according to claim 1, wherein, in step (A), the image is also encoded into the current encoded image based on a previous encoded image, and the image is encoded in a frame And one of the inter-frame coding techniques, when the result of the determination is that an action event has occurred and the occupancy rate of the temporary storage unit is greater than the threshold, the following steps are also included after step (C): (D ) Determine whether the current encoded image is encoded with the in-frame encoding technology; and (E) when it is determined that the current encoded image is encoded with the in-frame encoding technology, store the current encoded image stored in the storage unit to the temporary storage Unit as the image to be transmitted. The video bit rate transmission control method according to claim 1, wherein, in step (C), when the result of the determination is that an action event is determined and the occupancy rate of the temporary storage unit is not greater than the threshold, Store the current encoded image in the temporary storage unit as the image to be transmitted, and the bit rate of the encoded image encoded by the encoding parameter before update is less than the bit of the encoded image encoded by the updated encoding parameter Yuan rate. The video bit rate transmission control method according to claim 1, wherein, in step (C), when the determination result is that no action event is determined and the occupancy rate of the temporary storage unit is greater than the threshold, Store the current encoded image in the temporary storage unit as an image to be transmitted, the bit rate of the encoded image encoded by the encoding parameter before update is greater than the bit rate of the encoded image encoded by the updated encoding parameter rate. The video bit rate transmission control method according to claim 1, wherein in the step In step (C), when the result of the determination is that no action event occurs and the occupancy rate of the temporary storage unit is less than the threshold, the current encoded image is stored in the temporary storage unit as the image to be transmitted , The bit rate of the encoded image encoded by the encoding parameter before the update is greater than the bit rate of the encoded image encoded by the updated encoding parameter. The video bit rate transmission control method as described in claim 5, after step (C), further includes the following steps: (F) determining whether the storage unit stores a previously encoded image; and (G) when the storage is determined When the unit stores the previous encoded image, the previous current encoded image stored in the storage unit is stored in the temporary storage unit as the image to be transmitted. The video bit rate transmission control method according to claim 1, wherein, in step (A), the image is also encoded into the current encoded image based on a previous encoded image, and the image is encoded in a frame And one of the inter-frame coding techniques, the following steps are also included between step (A) and step (B): (H) determine whether the currently coded image is coded with the intra-frame coding technique; and (I) When it is determined that the currently encoded video is encoded with the in-frame encoding technology, the currently encoded video is encrypted.

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